The migration of neutrophils (PMN) and monocytes in response to chemotactic factors (CF) and the subsequent production of toxic oxygen intermediates are critical to host defense against bacteria and tumors. CF stimulate the oxidative burst and enhance the production of O2 by PMN upon subsequent stimulation with phorbol myristate acetate or opsonized zymosan. We have found this enhanced activity is due to a quantitative increase in the membrane oxidase. Stimulation of PMN with CF (C5a, f-Met-Leu-Phe) also triggers a bimodal chemiluminescence response. We have found that this bimodal response represents a 1~ response at 1 to 2 min due to O2 generation and a 2~ response at 5 to 10 min dependent upon myeloperoxidase release. In an effort to analyze simultaneously chemotactic-receptor binding and cell function, we have produced fluorescent C5a, f-met-leu-phe, and casein derivatives that retain their biologic activity. These factors bind to greater than 90% of PMN, greater than 70% of monocytes, and less than 10% of lymphocytes, and binding is specific for each factor. Data indicate that these receptors are independent and simultaneously present on PMN and monocytes. These probes are being utilized with flow cytometry assays for NADPH, H2O2 production, and phagocytosis to analyze the mechanism of activation of the respiratory burst. The mechanism for attracting lymphocytes to a site in vivo is unknown. We have now defined a human T-lymphocyte CF made by T cells in response to mitogen or antigen. This CF is a peptide of approximately Mr = 14,000, which is produced by human helper/inducer T cells and specifically attracts suppressor/cytotoxic T cells. Studies in patients indicate that in vitro migration of T lymphocytes in response to casein or T-lymphocyte CF is suppressed in patients with established malignancy but not in patients with benign tumor. Evidence suggests that this inhibited migration is due to a direct action of a suppressor cell population. Suppressed T migration in patients with malignancy may partially explain decreased cellular immunity in the patients. (LB)